Snow Water Equivalent Reconstruction Using FIA Tree Ring Data

Abstract:

Tree ring widths have been used as a proxy for climate variables for several decades. Temperature, precipitation, and less commonly, snow water equivalent have been modeled in numerous locations throughout the world. Typical studies use carefully selected trees to maximize length of record and sensitivity to the variable of interest, and result in a reconstruction for a specific location. Here we use tree ring data collected by the Forest Inventory and Analysis (FIA) program, conducted by the U.S. Forest Service to reconstruct snow water equivalent for the state of Utah. This program collects increment cores on a geographically unbiased grid at horizontal resolution of 5-km across the U.S., resulting in an unprecedented sample density of tree ring data, and therefore enabling a reconstruction that covers a large geographic area at a resolution not possible using traditional dendroclimatology methods. Prior work (DeRose et al. 2013) has shown FIA to have coherence with previously published chronologies and with water-year precipitation. Snowpack is a major source of water in the Intermountain West, and yet few tree ring studies have reconstructed SWE and the instrumental record is limited in length, so this reconstruction represents a novel and useful dataset for water users and resource managers alike. Here we present initial results and a preliminary analysis of this unique dataset.